How to turn plastic waste into diesel fuel cheaply

[imakebiodiesel]

MrJohnson mentioned using Iron hydroxide as a catalyst, perhaps he might explain how it could be used.
Another possible way is explained below. I should say that this is only a proposal for consideration, I have never tried it and probably never will since I dont need to process PET. The vapours would be kept above 300C in the reflux column and then bubbled through diesel at 200C. the terephthalic acid would sublimate and sink to the bottom of the tank. The heavy and middle fractions would condense in the diesel and overflow through the u bend. Light fraction vapours would pass up through a cold condenser and the uncondensed gases would pass on to the bubbler.
What do you think, would this work?


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[Beyond Biodiesel]

The batch size was 1kg and the exit pipe was 1 inch. At the time my pressure relief valve was positioned at the top of my reflux column so it got blocked as well. After that incident I fitted the pressure relief valve on it own pipe direct to the retort, a much safer arrangement.

Wow! Good to know that the exit pipe has to be large. Yes, I have pondered installing a pressure relief valve, and considered it needed to be on its own pipe from the retort, because it would be all too easy to coke it up if it was on the exit pipe.

Soiled, unsorted PE,PP and PS on the other hand is worth almost nothing and is ideal for our process. Thats why my short answer to Pravins question was no.

Yes, cost effectiveness is good to keep in mind. The reason why I am focused on distilling WMO is because I have 200 gallons of it on hand, and I regularly get offers for hundreds of gallons more; and with WMO 5 gallons in is nearly 5 gallons of fuel out.

Hi,

With this unit I will plan to crack only PE, PP, LDPE, HDPE materials. Also in the pressure sensor will be installed in reactor. When the pressure sensor is triggered a rise in pressure system, the entire system will be switched off.
Thanks for the idea you notice about the bubbler. I think somewhere can be kind of gas meter installed. In cases where the meter stops, the unit also will be switched off.
Best regards.

I think a gas meter is a good idea, so I am looking for one. A flow meter can be useful as well.

Another possible way is explained below. I should say that this is only a proposal for consideration, I have never tried it and probably never will since I dont need to process PET. The vapours would be kept above 300C in the reflux column and then bubbled through diesel at 200C. the terephthalic acid would sublimate and sink to the bottom of the tank. The heavy and middle fractions would condense in the diesel and overflow through the u bend. Light fraction vapours would pass up through a cold condenser and the uncondensed gases would pass on to the bubbler.
What do you think, would this work?

Bubbling the gasses through diesel fuel at 200c when processing PET to remove the terephthalic acid seems reasonable, but all of us learning from your experience that pipe going through the diesel would have to be pretty large, maybe 2"

[fibuslitero]

The japanese company Blest says that the pipes must be heated about 600º in order to avoid collapse with PET.
That means much more energy but seems to be a solution.

There are also documents that say that Ca(OH)2, KOH and NAOH neutralize undesired acids derived from PET pyrolisis in lab setups and at industrial scale.
Since PET does not yield good fuel the better way to deal with it is avoiding it in the feedstock and neutralizing what it may appear.
There is also a japanese company that says its method allows 10% of pvc, pet and other plastics (that contain oxygen and heteroatoms).
I think that the process simply and fortunately allows this contamination itself and an alkaline catalyst just helps to neutralize any acid in that % .

There are patents claiming to obtain active carbon derived from PET pyrolisis using NaOH and KOH as catalyst/neutralizer.

MrJohnson mentioned using Iron hydroxide as a catalyst, perhaps he might explain how it could be used.
Another possible way is explained below. I should say that this is only a proposal for consideration, I have never tried it and probably never will since I dont need to process PET. The vapours would be kept above 300C in the reflux column and then bubbled through diesel at 200C. the terephthalic acid would sublimate and sink to the bottom of the tank. The heavy and middle fractions would condense in the diesel and overflow through the u bend. Light fraction vapours would pass up through a cold condenser and the uncondensed gases would pass on to the bubbler.
What do you think, would this work?


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[mjohnson1]

From my understanding, Iron (III) oxide-hydroxide (FeOOH) can be used as a catalyst to break down the terephthalic acid into benzoic acid and then into various liquids.

The suggested procedure for this is to have FeOOH in a steam atmosphere. The PET would then undergo pyrolysis and the FeOOH can do its job. The FeOOH catalyst should be used so that it comes into contact with the PET gasses. I am not sure of the practicality of using FeOOH mixed in with the solid PET.

Keep in mind I have not done any pyrolysis of PET as I don't see it as a viable plastic source for my area. I intend to continue focusing on the other plastic types. This is just my understanding from reading various experiments, journals, etc.

The pipe diameter is not the biggest concern here as even a larger diameter pipe would eventually succumb to the effects of terephthalic acid and result in a blockage. You are basically delaying the inevitable unless you clean all the pipes out after each batch. You can keep everything above 300C but then you run into problems distilling the fuels at their respective temperatures.

[pravin]

TO ImakeBD, I have a feeling that terephthalic acid will not travell till the bubler. It might solidify in the tube or at the tip of bubler. The temp at my reflux was @ 400C then to it had soldified on the tip of reflux deleviry tube.

[mjohnson1]

Here is a link to an eBay auction for some FeOOH if anyone is interested:

2 lb Yellow Iron Oxide Feooh Ochre | eBay

[teegoenergy]

i want to say a big thank you ,,,, all your interligent guys in this forum... am working on my machine..

[imakebiodiesel]

If its necessary to maintain the reflux column at 400C then it will not function as a reflux at all. The partially cracked vapours will pass straight through the column and clog the condensers with wax, which is just a dangerous a situation.
As Ive said before Im not sure that the extra trouble of processing PET is worth it, considering its high value and the availability of cheap PE,PP and PS.
The size of pipes connecting the parts of the reactor are very important and not easy to calculate. The gas must be able to flow smoothly through the system without bottle necks. I would advise to err on the side of caution and always select large size pipes without sharp bends.
I have found that the best pipe for our purposes is plain steel threaded pipe with steel threaded fittings sealed with high temperature silicone mastic. Stainless steel is good but not any better. Avoid copper or galvanized pipe. Obviously plastic pipe is not suitable anywhere on the system.

[pravin]

IMBD The temp at reflux was not maintained but went up as the pressure builtup due to clogging of delivery tubes.

[khouchaymi]

Carbon Black

My questions:
1- does pyrolysis of plastic leaves behind carbon black like tyres? if yes what is the percentage
2- can waste vegitable oil (WVO) be used in pyrolysis like waste motor oil (WMO)?

[kaguar]

I tried to pyrolyze WVO. With catalyst you get fuel very similar to diesel, and without you get very stinky liquid. Probably it depends on the oil you use. I used a mixture of various wvos.

[otpadnoulje]

Hi Kaguar!

Did you try palm oil?

[imakebiodiesel]

If I carry the pyrolysis process to the very end, with catalyst, I am left with 8 grams of char per kilo of plastic. I have has this analysed by mass spectrometry and gas chromatograph and it is 98% carbon, so yes it is carbon black. However I have found that it is much more energy efficient to extract only 1.1 litres of fuel from each kilo and the residue is a quantity of soft black wax. This wax can be mixed with waste wood shavings and sawdust. When molded into blocks it burns cleanly and without smell in a wood stove.

The idea of pyrolyzing veg oil seems a strange one. The esters in most veg oils are of roughly the same molecule length, average C17, as diesel fuel so cracking, either thermal or catalytic, will not achieve anything useful. The problem with veg oil as a motor fuel is the presence of glycerol but pyrolysing will not eliminate this. Esters will gasify at 400C before the glycerol 750C leaving behind the stinking tarry mess mentioned above.

[DrGoldSmith]

How did I manage to crack and seperate fractions?

So, it seems I got lucky with my setup... You see, the kjeldahl bulb acted as the perfect reflux. As the cracking occurred in the boiling flask the bulb would continue to condense and return (reflux) the liquid to the boiling flask. The liquid in the bulb would start as a clear color and the temp would gradually rise over time the liquid would change to a yellow then an orange then brown... You could see that the only vapors that escaped the bulb would correspond to the temp of the bulb and it seems that the temp would only rise as the fractions completely boiled off.

I must admit that this was a complete accident that I had the sizes, amount of feedstock and temp all just right for this to occur as it did... As I changed parameters in subsequent experiments I could see varying results in the output, particularly in the ability to cleanly separate fractions. On warmer days or with more heat I would see a mix of fractions coming out at the same time as I noted a higher bulb temperature that occurred quicker in the process.

I suppose the setup can be designed and automated to control the direction of the output so as to separate the output into its fractions however the size of the bulb is a key to making it work correctly. Additionally, adding a heating/cooling control of the bulb would help.

I have experimented with heating the bulb to keep it at the cracking temp and my output would end up as a dark orange brown wax. I have distiller the fractions out as a secondary process and the results were quite good but I did discover something interesting as I heated the wax to a liquid- the wax would pop violently as it was heated... It requires a very slow heating and a lot of caution or it appears that it will explode! Once it is completely liquid it still takes some time before the popping and bursting stops. I have some theories as to what is happening but I wonder if anyone knows what this is really doing?

[mjohnson1]

Can anyone help me out with devising an auger feed system that would work with purge gasses?

I have a 1 1/2 inch auger and a steel pipe to house it. It works fine but I can't connect it to the reactor until I can figure out a purge system. I plan on using CO2 for the purge gas but N2 can also be used.

I have seen systems with an open hopper that still purges the oxygen i'm just not sure how to design it.

I'm thinking a premelt system would be the solution with electric/gas heating that just gets the plastic to liquid form.

The plastic would not have empty space then like in solid form.

Can anyone think of another way of going about this? Any advice would be appreciated.

Here's a diagram of my idea: